I live in Texas. Our electricity delivery is quite complicated. I moved here from California where our only choice was to have PG&E or no power. We paid what they told us to pay, and we said, “thank you.” It was simple. But in Texas, you have different choices for power companies. Where I live, I have about a dozen or so choices for companies, and each one has multiple pricing schemes. So you could have a pricing scheme that is a flat rate, or you could have ones that have time-based tiers, or usage tiers, etc. I’m sure someone offers a pricing scheme that roughly follows the market prices, but honestly you’d be dumb for choosing that one. Most people go with tiered usage ones because they appear to be the lowest prices. So you pay based on how much you use, but the more you use, the more you pay.
I have solar panels, and when choosing a power plan that works best for that, I did see many that purchased your excess power based on the market price. Usually it was like some percentage of the market price, not 100%. However I ended up going with a time-based pricing scheme where my power is free between 9 PM and 7 AM, as my solar panels and batteries cover me for the rest of the time. I essentially pay nothing for power, and I have an electric car, electric dryer, and electric oven.